Azobenzene reductase also known as azoreductase () is an

enzyme An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...

that

catalyzes Catalysis () is the increase in rate of a chemical reaction due to an added substance known as a catalyst (). Catalysts are not consumed by the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quick ...

the

chemical reaction A chemical reaction is a process that leads to the chemistry, chemical transformation of one set of chemical substances to another. When chemical reactions occur, the atoms are rearranged and the reaction is accompanied by an Gibbs free energy, ...

: :N,N-dimethyl-1,4-phenylenediamine + aniline + NADP⁺

\rightleftharpoons

4-(dimethylamino)azobenzene + NADPH + H⁺ The 3 substrates of this enzyme are N,N-dimethyl- 1,4-phenylenediamine,

aniline Aniline (From , meaning ' indigo shrub', and ''-ine'' indicating a derived substance) is an organic compound with the formula . Consisting of a phenyl group () attached to an amino group (), aniline is the simplest aromatic amine. It is an in ...

, and

nicotinamide adenine dinucleotide phosphate Nicotinamide adenine dinucleotide phosphate, abbreviated NADP or, in older notation, TPN (triphosphopyridine nucleotide), is a Cofactor (biochemistry), cofactor used in anabolic reactions, such as the Calvin cycle and lipid and nucleic acid synt ...

ion, whereas its 3

products Product may refer to: Business * Product (business), an item that can be offered to a market to satisfy the desire or need of a customer. * Product (project management), a deliverable or set of deliverables that contribute to a business solution ...

are 4-(dimethylamino)

azobenzene Azobenzene is a photoswitchable chemical compound composed of two phenyl rings linked by a azo compound, N=N double bond. It is the simplest example of an aryl azo compound. The term 'azobenzene' or simply 'azo' is often used to refer to a wide c ...

, and

hydrogen ion A hydrogen ion is created when a hydrogen atom loses or gains an electron. A positively charged hydrogen ion (or proton) can readily combine with other particles and therefore is only seen isolated when it is in a gaseous state or a nearly particl ...

. This enzyme belongs to the family of

oxidoreductase In biochemistry, an oxidoreductase is an enzyme that catalyzes the transfer of electrons from one molecule, the reductant, also called the electron donor, to another, the oxidant, also called the electron acceptor. This group of enzymes usually ut ...

s, specifically those acting on other nitrogenous compounds as donors with NAD+ or NADP+ as acceptor.

Mechanism

The reaction catalyzed by this enzyme proceeds via a

ping-pong mechanism Enzyme kinetics is the study of the rates of enzyme-catalysed chemical reactions. In enzyme kinetics, the reaction rate is measured and the effects of varying the conditions of the reaction are investigated. Studying an enzyme's kinetics in thi ...

by using 2 equivalents of NAD(P)H to reduce one equivalent of the

azo compound Azo compounds are organic compounds bearing the functional group diazenyl (, in which R and R′ can be either aryl or alkyl groups). IUPAC defines azo compounds as: "Derivatives of diazene (diimide), , wherein both hydrogens are substituted ...

substrate (for example

methyl red Methyl red (2-(''N'',''N''-dimethyl-4-aminophenyl) azobenzenecarboxylic acid), also called C.I. Acid Red 2, is an indicator dye that turns red in acidic solutions. It is an azo dye, and is a dark red crystalline powder. Methyl red is a pH indica ...

where Ar = ''p''-

dimethylaniline ''N'',''N''-Dimethylaniline (DMA) is an organic chemical compound, a substituted derivative of aniline. It is a tertiary amine, featuring a dimethylamino group attached to a phenyl group. This oily liquid is colourless when pure, but commercial ...

and Ar' = ''o''-

benzoic acid Benzoic acid () is a white (or colorless) solid organic compound with the formula , whose structure consists of a benzene ring () with a carboxyl () substituent. The benzoyl group is often abbreviated "Bz" (not to be confused with "Bn," which ...

) into two equivalents of

product: : Ar–N=N–Ar' + 2(NAD(P)H + H⁺)

\rightleftharpoons

Ar–NH₂ + NH₂–Ar' + 2NAD(P)⁺

Substrate specificity

Most azoreductase isoenzymes can

reduce Reduction, reduced, or reduce may refer to: Science and technology Chemistry * Reduction (chemistry), part of a reduction-oxidation (redox) reaction in which atoms have their oxidation state changed. ** Organic redox reaction, a redox reacti ...

methyl red, but are not able to reduce

sulfonated In organic chemistry, aromatic sulfonation is a reaction in which a hydrogen atom on an arene is replaced by a sulfonic acid () group. Together with nitration and chlorination, aromatic sulfonation is a widely used electrophilic aromatic substi ...

azo dyes. The unique azoreductase

isozyme In biochemistry, isozymes (also known as isoenzymes or more generally as multiple forms of enzymes) are enzymes that differ in amino acid sequence but catalyze the same chemical reaction. Isozymes usually have different kinetic parameters (e.g. di ...

from ''

Bacillus ''Bacillus'', from Latin "bacillus", meaning "little staff, wand", is a genus of Gram-positive, rod-shaped bacteria, a member of the phylum ''Bacillota'', with 266 named species. The term is also used to describe the shape (rod) of other so-sh ...

'' sp. B29 has the ability to reduce sulfonated azo dyes however.

Nomenclature

The

systematic name A systematic name is a name given in a systematic way to one unique group, organism, object or chemical substance, out of a specific population or collection. Systematic names are usually part of a nomenclature. A semisystematic name or semitrivi ...

of this enzyme class is N,N-dimethyl-1,4-phenylenediamine, aniline:NADP+ oxidoreductase. Other names in common use include: * azo reductase, * azoreductase, * azo-dye reductase, * dibromopropylaminophenylazobenzoic azoreductase, * dimethylaminobenzene reductase, * methyl red azoreductase, * N,N-dimethyl-4-phenylazoaniline azoreductase, * NAD(P)H:1-(4'-sulfophenylazo)-2-naphthol oxidoreductase, * NADPH2-dependent azoreductase, * NADPH2:4-(dimethylamino)azobenzene oxidoreductase, * NC-reductase, * new coccinea (NC)-reductase, * nicotinamide adenine dinucleotide (phosphate) azoreductase, * orange I azoreductase, * orange II azoreductase, * p-aminoazobenzene reductase, and * p-dimethylaminoazobenzene azoreductase.

Structural studies

As of late 2007, 3

structures A structure is an arrangement and organization of interrelated elements in a material object or system, or the object or system so organized. Material structures include man-made objects such as buildings and machines and natural objects such as ...

have been solved for this class of enzymes, with PDB accession codes , , and . Please check the last updated data o
RCSB PDB site

Mechanism

Substrate specificity

Nomenclature

Structural studies

References

Further reading